Objectives: 1. We plan several physical chemical studies on factors influencing DNA renaturation kinetics. 2. The effect of mismatches on the kinetics and Tm is already under way in our laboratory. Hydoxylamine reacted with cytosine is used to make the mismatches. 3. Theory and experiments on deviations from second-order kinetics observed for more complex DNA are underway also. 4. We will try to eliminate excluded volume effects by running renaturation kinetics in ideal solvents, hopefully increasing the rate of reaction several-fold.